258 THE WORLD OF LIFE 



it was carnivorous (see Fig. 93). True carnivorous mar- 

 supials allied to the ^' Tasmanian wolf" (Thylacinus) and the 

 Tasmanian devil {Sarcopliilus) are also found. 



Fig. 93. — Skull of Thylacoleo carnifex. 

 From the Pleistocene of Australia. One-fifth nat. size. (B.M. Guide.) 



How and when the marsupials first entered Australia has 

 always been a puzzle to biologists, because the only non-Aus- 

 tralian family, the opossums, are not closely allied to any of 

 the Australian forms, and it is the opossums only which have 

 been found in tlie European early Tertiaries. But recent dis- 

 coveries in South America have at length thrown some light 

 on the question, since the Santa Cruz beds of Patagonia (Mid- 

 dle Tertiary) have produced several animals whose teeth so 

 closely resemble those of the Tasmanian Thylacinus that Mr. 

 Lydekker has no doubt about their being true marsupials allied 

 to the Dasvurid^e. There is also, in the same beds, another 

 distinct f amilv of small mammals — the Microbiotheridge of 

 Dr. Ameghino — which, from a careful study of their denti- 

 tion, are also considered by Mr. Lydekker to be " polypro- 

 todont marsupials of an Australian type." ^ 



But even more important is the discovery of living mar- 

 supials of the Australian rather than the American type in the 

 very heart of the South American fauna. In 1863 a small 

 mouse-like animal of doubtful affinities was captured in Ecua- 



lA Geographical Historj^ of Mammals, p. 109. 



